过量表达烟酸转磷酸核糖激酶对大肠杆菌NZN111产丁二酸的影响

Effect of overexpression of nicotinic acid phosphoribosyl transferase on succinic acid production in Escherichia coli NZN111

摘要:

大肠杆菌NZN111厌氧发酵的主要产物为丁二酸，是发酵生产丁二酸的潜力菌株。但是由于敲除了乳酸脱氢酶的编码基因 (ldhA) 和丙酮酸甲酸裂解酶的编码基因 (pflB)，导致辅酶NADH/NAD+不平衡，厌氧条件下不能利用葡萄糖生长代谢。构建烟酸转磷酸核糖激酶的重组菌Escherichia coli NZN111/pTrc99a-pncB，在厌氧摇瓶发酵过程中通过添加0.5 mmol/L的烟酸、0.3 mmol/L的IPTG诱导后重组菌的烟酸转磷酸核糖激酶 (Nicotinic acid phosphor

Abstract:

Escherichia coli strain NZN111 is a promising candidate for the fermentative production of succinate. However, because lactate dehydrogenase and pyruvate formate lyase were inactivated in NZN111, this strain had an unbalanced NADH/NAD+ ratio and could not use glucose under anaerobic conditions. In this study, a recombinant strain E. coli NZN111/pTrc99a-pncB was constructed to overexpress the nicotinic acid phosphoribosyl transferase gene (pncB). Under anaerobic conditions with the addition of 0.5 mmol/L nicotinic acid and 0.3 mmol/L isopropyl beta-D-thiogalactopyranoside (IPTG), the specific nicotinic acid phosphoribosyl transferase (NAPRTase, EC 2.4.2.11) activity in the recombinant strain was 11-fold higher than that in E. coli NZN111, the concentration of NAD(H) was increased by 3.85-fold, especially the concentration of NAD+ was increased by 5.17-fold and NADH/NAD+ was decreased from 0.640 to 0.125. The recombinant strain regained the capability of growth and glucose utilization under anaerobic conditions.